Electric circuit breaker



Feb. 17,1948. .1. w. TlMMERMAN, JR

ELECTRIC CIRCUIT BREAKER Filed Nov. 7, 1944 2 Sheets-Sheet 2 HisAttqr-ney- Inventor. Julius W. TimmermamJrr,

Patented Feb. 17, 1948 Julius W Timmerman, Jr. Springfield, Pa assignorto General, Electric ,(lon panmqacoijporation, of N ew:. YorkApplication'November 7, 1944, Serial N0.'562,297 8 Claims. (01.200-82) i-My invention relates to electric; circuit break- "ers, and moreparticularly. tooperating mechal nisms for electric circuit breakers, ofthe lfiilid operated type. Specifically myqinvention is an improvementon. .the circuit breaker 1 operating mechanism disclosed and .claimedin.copending 1 application Serial .No. 562,296,;Eoisseau, and, Bold, filedconcurrently with thew-present application and assigned to the sameassignee asxthe. present 2 application.

A pneumatic or. fluid operatedmechanism for an electric circuitbreakershould; provide-controlled opening forces thatproducea high initialacceleration for: rapidly separating the contacts and providing :thenecessaryiiorces ior'opening blast valves and the likeif.thecircuitbreaker is an air or'fiuid blasticircuit breaker. Theopeningspeed should not beiincrea'sedby virtue of the fluid blast. at the.contacts. within the arc chutes actingupon the movable contacts; as ad:ditional eflective. pistons. :speed be. decreased by. opposing forcesencoun- Neither should, the

tered duringthe opening stroke. :-Near,the end oi the opening strokeitis furthermore desired that the speed be gradually, decreased by; asuit-l able dashpot arrangement.

Accordingly, it is an .object .of. my invention. to provide a newandimproved fluid-operated. operatingmechanism fOllElGCtllC circuitbreakers.

It is another object .of. my invention to provide. a. fluid operated.operatingmechanism .for electric circuit breakerswhichprovides-controlled 1 pneumatic opening. forces which produce.ahigh l initial acceleration. .forrapidly. separating, the

breaker contacts .to a desiredopeningspeedwhich, :.is graduallydecreasedafter thearcinggperiod until the contacts are'arrested by afinal dashpotaction despite the assisting or opposing forces which mightact thereon.

.Still ,anotherobject ofmy. invention is to pro-.

vide anew and improved fluid operated operating mechanism for air,blast, circuit, breakers which is simple'and compact andwhich providesallithe speed control vfunctions of accelerating,

- retarding,i;etc.,, throughout the operating strokes;-

Furthercbjects and advantagesof my invention-will become apparent asthefollowing deuscription proceeds and the features of novelty whichcharacterize my invention; will be pointed 2 out with particularity inthe claims annexed-to and forming a part of this specification.

.For a better understanding of .myinvention reference ,may-behadto the"accompanying drawings-in which'Fig. 1 is:anelevational-view, :.partly in:section, .of; an ielectricicircuitbreaker embod ing, the operatingmechanism of my invention; Fig. 2 is'a side view ofFig. 1; Fig. 3 is anenlarged perspective view, partly in section, of the operating mechanismof Fig., 1, and Fig. 4

; is an, enlarged view, partlyin section, of another .portion, of. theoperatingmechanism of my invention.

,Aswisdiscussed in the above referred to concurrently; filed copendingapplication, my inven- @tion is also particularly applicable topolyphase circuit breakers although itcan equally well be .usedpnasingle phase circuit breaker.

. trated my. inventio as applied to an electric circuit breaker which isparticularly adapted for usewith metal-clad switchgear. Accordinglyg Ihave illustrated a metal housing I within which is mounted a suitablearc chutev 2, preferably supported on an insulator 3 suitably fastenedto the base 4 ofhousi'ngl.

,In accordance with the disclosure of Bold Patent 2,362,798,;grantedNovember 14, 1944, and assigned to the same assignee as the present ap-;plication; the circuit breaker includingthe housing l constitutes aunit assembly with the interrupting structure,.including the arc chute2, at

the lower end of the housing and the operating mechanismgenerally'indicated at 5 supported at p the u per end of the housing. Asillustrated, the

operating mechanism 5 and the source of fluid 1 under pressure indicatedonthe drawing as tank 1 6 are supported;fromsuitable channel irons Iloathe top of housing I. As in the above men- .tioned Bold patent, apair of horizontal ducts 8 and 9- are mounted intermediate the arc chute2 and the operating mechanism 5. The exhaust gases from the arcchutes,such as 2, therebeing three such are chutes. for a three-phase breaker,are led through exhaust gas conduits such as [0, into. ducts. 8 and 9.which are suitably interconnected. These ducts B and 9 are connected to7 atmosphere, .as is disclosed in the above mentioned Bold patent.Housing lis provided with a .plura1ity of openingssuchas ll,arranged'between ducts 8and 9, through which the operating mechanism maybe connected with the relatively moving contacts associated with are 1chute 2.

, Arc chute 2 preferably comprises the well known cross gas blast typeof arc extinguishing structure, such for example as is disclosed. in

United States Letters Patent 2,284,842, Prince et al granted June 21',.1942, and assigned to the same assigneeu as the present application.This ar,c,.,chute maybe constructed in accordance with closing strokes.

the arrangement disclosed and claimed in copending application, SerialNo. 586,892, filed April 6, 1945, also assigned to the same assignee asthe present application. Associated with the arc extinguishingstructure, or are chute 2, are a pair of relatively movable contactscomprising stationary contact l2 mounted within arc chute 2 and movableblade contact I3 adapted to engage the stationary contact l2 in arcchute 2 when the circuit breaker is in the closed position indicated inFig. 1. Stationary contact I2 is con-'- nected by suitable conductors I4and I5 with terminal l6 mounted exteriorly of housing a suitableinsulator I! being provided to insulate the housing I from the liveconductor. Similarly, movable contact I3 is connected by suitable.sliding contact means with line terminal 18 through conductors I9 and20, conductor 20 being suitably insulated in its passage through housingby an insulator 2|.

Straight line motion of movable contact I3 is obtained by virtue of aplurality of rollers 22, two rollers adapted to be engaged with eitherside of contact l3. 'Preferably rollers 2-2 are mounted in a suitablehousing supported from.

an insulator 23, which in turn is mounted within I housing I in anysuitable manner.

constructed of insulating material so that the tank 6 and the operatingmechanism 5 are maintained at ground potentialand are completelyinsulated from the'current conducting parts of the electric circuitbreaker. A suitable blast valve generally indicated at 2B, and bestshownin Fig. 4, is mounted adjacent the point where conduit 24 enterstank 6. This blast valve 26 as is clearly indicated in Fig. 4, comprisesa reciprocally movable valve member 21 fastened to 'a valve stem 28. Aspring 29 normally biases valve member 21 to the closed positionindicated in Fig. 4.

The new and improved operating mechanism 5 of my invention comprisesparallel, double ended pistons and associated cylinders which drive andcontrol the circuit breaker opening and As illustrated, the operatingmechanism 5 which is essentially a plurality of fluid motors, comprisesa main circuit breaker opening piston'30 and a circuit breaker closingpiston 3| rigidly interconnected and suitably spaced from each other bya rack 32. Piston 30 is reciprocal in a cylinder 33 while piston 3| isreciprocal in a cylinder 34. Preferably these cylinders 33 and 34 arearranged as one continuous cylinder with a discontinuous portion so thata pinion 35 fixedly mounted on a-horizontal, rotatable shaft 36 engageswith rack 32. Reciprocal movement of pistons 30 and 3| causes rotationof pinion 35 and associated shaft 36.

In order to provide accurate speed control of the fluid motor, includingmain operating pistons 30 and 3|, I have provided another set of pistons31 and 38 rigidly interconnected by a rack 39. Pistons 31 and 38 aremounted in cylinders 40 and 4|, respectively, which like cylinders 33and 34, are preferably arranged as one continuous cylinder parallel withthe continuous cylinder comprising cylinders 33 and 34. It will beobvious that with this arrangement when-' a ever pistons and 3| aremoved to the right, as viewed in Figs. 1 and 3, pistons 31 and 38 willbe moved to the left by virtue of pinion whose teeth engage with bothracks 32 and 39.

Pistons 31 and 38 provide a very desirable means of controlling thespeed of operation of the operating mechanism 5 during an operatingstroke of the circuit breaker, and eliminate the requirement of anyseparate dashpots or retarding devices as was required in prior artarrangements. Cylinder 40 is provided with a suitable needle valve 42,While cylinder 4| is provided with a suitable needle valve 43.

the desired dashpot action, as will be described in greater detailhereinafter.

ing or main operating pistons, as of the same size as pistons 31 and 38,which in effect are compensating pistons, it will be obvious thatpistons 30 and 3| may be larger than pistons 31 and 38 to ensurepositive full opening and full closing operations.

The operating mechanism of any circuit breaker during the openingoperation requires a relatively large initial force in order to separatethe relatively movable contacts which are usually in frictionalengagement. In addition an air blast circuit breaker such as isdisclosed, usually requires additional forces to open the blast valve aswill be described hereinafter. As soon as the contacts have separatedand a blast of fluid is supplied in arc chute 2 for arc extinguishingpurposes this fluid acts on movable contact l3 just as if movablecontact l3 were a piston. If

' a constant force were applied against opening piston 30 suflicientlylarge to initially move contact I3 toward the open position, it isobvious that the air blast within arc chute 2 would soon assist piston30 and cause contact l3 to move at a greatly increased speed. In orderaccurately to control the speedof movable contact I3 I provide anaccelerating means comprising a booster or kick-off piston 44conveniently mounted in a cylinder 45 coaxial with cylinder 33 andclosely adjacent the end thereof. Piston 44 is provided with a pistonrod 46 extending through the end of cylinder 33 so as to engage openingpiston 30. Fluid under pressure from source 6 is provided in cylinder 45through conduit 41 and circuit breaker opening valve 48. When circuitbreaker opening valve 48 is open fluid under pressure enters cylinder 45and causes booster piston 44 to move to the right. Any fluid in cylinder45 ahead of piston 44 escapes. to atmosphere through escape port 49.Although I have illustrated booster piston 44 as having the samediameter as main opening piston 30, it will be understood that piston 44may have any size desired so as to provide the initial force which isdesired.

In order to provide accurate speed control, predetermined points incylinders 45 and 33 are the open position fluid under pressure issupplied to circuit breakerclosing piston 3| from source 6 throughconduit 53 and circuit breaker closing 7 These needle: valvesinterconnect the respective cylinders with atmosphere and may besuitable adjusted to give,

Although I have illustrated pistons 30 and 3| which are the drivvalve54. QE'OI proper. speedeoptrol cylinder 3,4, within which piston; 3|reciprocates, is provided with an adjustable needle valve 55' and a pairof j dump ports 56 thepurpose, ofwhich will become apparent from thefollowing description. I,

With the-above described arrangement the movable contacts .of apolyphase circuit breaker,

"such as 13, may readily beconnected to operatingmechanism so as toprovide a very. simple .and compact arrangement, Asillustrated in ,Figs.

. land 2, the horizontally mounted shaft 36 rotatable with; pinion '35'-is,"providedgw ith, suitable crank arms 5.! rigidly fastened to shaft36 at r The free ends of crank arms 51 are pivotally connected as isindicated at 58 with links 59. As indicated in Fig. 1, each link 59comprises a' section 59' of insulating materi'aland a goose-neckportion' 59" between crank' o arm 51 and-insulation 59. The other end oflink 59"is" pivotally connected, as is. indicated at 60, a with movableblade contact l3. It will be obvious that link 59- and crank arm 51provide an overcenter toggle arrangement which looks the cirf c'uitbreaker both in theopen 'and'in'the closed position.

' This lo'cki'n'gfeature is not my inven- 'tion but is'rnorefully'dis'clo'sed' and claimed in the above nien'tioned concurrentlyfiled, copending application of 'Boi'sse'au' 'andBold.

wing the above described operating mechanism "5,b-lastvalve '26 canreadily be operated in respouse to relative movement of the contactsn'ie're'ly by providing 9; c'am 'GIfiXedIy attached to shaft '36} seeFigs. 3 and 4. 'Cam 6I.m'ay be arranged to engage a roller""52 mountedon a bell 'crank 63 "pivotallymounted at 64 to an extension 65 ofmetalc'l'ad housin I. Bell crank 63 has an extension 56 'engag'eabIewith blast valve stem 28. 'Upon rotation'ofshaft 36 in clockwisedirection as "-vieWedin Figs. 3 and 4, ca'm' 6| causes bell crank 63 torotate' in a oounter clockwise direction' to open blast valve 26 andconsequently to provide ablast' of air' 'or" fluid underpressure"adjacent'relatively movablecontacts l2 and I3 before these contactshave' separated sufliciently "to draw an are therebetween.

1 1t should be understood that cut-off switches and the likecan also'becontrolled withthe above described "operating mechanism 5 merely byproviding additional cams on shaft 36.

' In order to understand how my new and *im- 'proved'operating mechanismprovides the desired speed control; the "opening operation of thecircuit breaker will first be described. With the ciro'uit' breaker'in'the closed position indicated in Fig'.- 1, the openingpperation isinitiated by opening circuit'breaker opening valve 48. It will beunderstood that this valve may be controlled in "any suitable manner,such aselectromagnetically or the like. A suitablecontrol system forvalves "'48: and 54 is'dis'closed and claimed in copending applicationSerial No. 589,288, Timmerman' and "Bold, filed April 20, 1945, andassignedto the same 'as'sig'nee as the'present' application. Upon I havefound it the prechargerli'ne. 5| is provided with a g'inch bore. It isobvious that with this arrangement and the fact that the volume to befilled in the spaced points therealong, the spacing depending I upon thespacingbetwee'n the poles of the poly' phase circuit. breaker.

booster cylinderi i5 is small; the vbmnief to be f lled in compensatingcylinder v4U is'large, the

pressure builds up rapidly behind the booster piston M which drives thepistons!) through pistonrod 41am the opening direction with an effectiveinitial force. h p i I 30 during the initial stagesbf the openingstroke, v for v the only airlpermitted to enter cylinder'33 for thedriving piston 30 must enter through,

needed as will become apparent as the following description proceeds. Y

During the stroke of booster piston 44, the blast valve member 21 hasbeen lifted by the cam GI and the main contacts I2 and [3 have separatedso that the air or fluid under pressure in the arc chute 2, acting onthe ,bOttOlIl of contact blade l3, now constitutes an effectiveauxiliary motor for moving the contacts toward'the open position. If athree phase breaker is considered, it will be appreciated that thisopening force acting on the three contact blades I3 is considerabl andtends to move the contacts'with greatly increased and possiblyundesirable speed as long as the blades [3 remain subject to thepressure within the arc chutes 2.

My invention in the particular embodiment being described is concernedwith providing speed control in this range between the time when'thefluid blasts in the arc chutes 2 may tend unduly to accelerate theopening movement of the circuit breaker and the moment at which theseblades withdraw from the arc chutes. Accordingly, toward the end of thestroke of the booster piston 44 the compensating cylinder Ml becomescompletely charged so that it begins to oppose the opening motion of thecircuit breaker. The size of the precharger line 5| to the compensatingcylinder 40 determines how soon and with what magnitude the openingcompensating piston 31 opposes the now predominating opening forcesapplied to the contact blades I3 by the fluid under pressure within arcchutes 2.

The interrupting operation takes place within the are chutes 2 while thecompensating piston 37 is holding down'the moving contacts to asubstantially constant speed to which they have been accelerated by theshort power stroke of booster piston 45. As the blades l3 withdraw fromthe arc chutes 2, the blast pressure is cut off bycam 6i so that thepiston effect'acting directly on the ends of the contact'blades isdiscontinued, thus making the retardation of compensating piston 31undesirabl'ebeyond this point; for it is preferable cylinder 40 toatmosphere.

to continue the opening movement at the same predetermined constantspeed. Accordingly, the restricted by-pa-ss 52 is located so that it isuncovered by the compensating piston 31 as the stroke, for therestricted by-pass 50 from the booster cylinder has permitted but agradual accumulation of air pressure behind'the piston 30 during thetime the contact blades l3 were supby-pass 52.

- sea 2 A final dashpot action takes place near the end of the openingstroke when the opening compensating piston 31 passes the second port ofthe The air remaining in cylinder 40 is compressed, giving the requireddecelerating force.

Needle valve 42 in the end of compensating cylinder so may be adjustedto allow the airto escape with the desired speed and at the same timeinsuring a positive full opening stroke. The needle valve 55 permits theair compressed in cylinder 34 during the circuit opening operation to;

escape.

A circuit breaker closing operation is initiated by opening circuitbreaker closing valve 54 whereupon fluid under pressure is admitted intocylinfluid motor to cause relative separation of said contacts, meansfor producing a blast of fluid adjacent said relatively movable contactsupon separation thereof to extinguish the arc drawn "between saidcontacts, said blast of fluid tending to aid theseparation of saidcontacts with one of said contacts effectively acting as a piston, meansfor introducing fluid under pressure only to said auxiliary fluid motorwith reference to said above mentioned fluid motors to cause movement ofboth of said pistons and relative separa tion of said contacts, meansfor arresting said piston of said auxiliary fluid motor after apredetermined movement thereof, means responsive to movement of saidpiston of said auxiliary fluid motor for causing fluid under pressure tobe introduced into said first fluid operated motor after a predeterminedmovement of both ofsaid pistons,

. a third fluid motor for opposing the operation der 3% to causemovement toward the left of pis-' 5 ton 3|. Dashpot action is exertedduring the end of the closing stroke by means of the closingcompensating or dashpot piston 38 in cylinder 4|. Compression of the aircontained in cylinder 4| at the beginning of the stroke affords thisl;

its closed position until the dump ports 56 are reached. At this point alarge portion of the air is exhausted to atmosphere thereby permittingtriprapid reversal of the pistons in the event of a free operation 'ofthe circuit breaker.

closing piston 3| drives the circuit breaker toward 'z While I haveshown and described a particular I embodiment of my invention, it willbe obvious to those skilled in the art that various changes andmodifications may be made without departing from my invention in itsbroader aspects and-I; T

therefore, aim in the appended claims to cover all such changes andmodifications as fall within the true spirit and scope of my invention.

What I claim as new and desire. to secure by Letters Patent of theUnited States, is: i

1. In an electric circuit interrupter comprising a pair of relativelymovable contacts, a first fluid operated motor including a cylinder, andpiston for producing relative movement of said contacts,

an auxiliary fluid motor including a piston ar--i ranged initially toapply amechanical force to said first fluid motor to cause relativeseparation of said contacts, means for introducing fluid under pressureonly to said auxiliary fluid motor with reference to said abovementioned fluid mo-L tors to cause movement of both of said pistons andrelative separation of said contacts, means including a cylinder foropposing the operation of said first fluid-operated motor during onlythe initial and final portions of the circuit interrupts,

ing'operation, means for supplying fluid under pressure to said lastmentioned cylinder prior to the introduction of fluid .under pressuretosaid first fluid motor, and means responsive to moveof said firstfluid-operated motor during the ini-- tial' and final portions but notduring theintermediate portion of the circuit interrupting operation,and means for supplying fluid under pressure to said third fluid motorsimultaneously with the introduction of fluid to said auxiliary fluidmotor.

3. In an electric circuit interrupter comprising a pair of relativelymovable contacts, a first fluid motor including a cylinder and pistonfor producing relative movement of said contacts, an auxiliary fluidmotor including a piston arranged initially to apply a mechanical forceto said first fluid motor to cause relative separation of said contacts,means for producing a blast of fluid adjacent said relatively movablecontacts upon separation thereof to extinguish the are drawn i betweensaid contacts, said blast of fluid tending to aid the separation of saidcontacts with one of said contacts effectively acting as a piston, meansfor introducing fluid under pressure only to said auxiliary fluid motorwith reference to said above mentioned fluid motors to cause movement ofboth of said pistons and relative separation of said contacts, means forarresting said piston of said auxiliary fluid motor after apredetermined movement thereof, means responsive to movement of saidpiston of said auxiliary fluid motor for causing fluid under pressureto;be introduced into said first fluid operated motor after apredetermined movement of both of said pistons, a compensating fluidmotor for compensating for the effect of said blast of fluid on said onecontact effectively acting as a piston, means for supplying fluid underpressure to said compensating fluid motor simultaneously with theintroduction of fluid to said auxiliary fluid motor,

and means for rendering said compensating fluid motor ineffective toretard said first fluid motor comprising a by-pass associated with saidcompensating fluid motor.

4. In an electric circuit interrupter comprising a pair of'relativelymovable contacts, operating means for said contacts comprising anaccelcrating means acting through a limited part of ment of said pistonof said auxiliary fluid motor for causing fluid under pressure to beintroduced into said first fluid operated motor after a preeterminedmovement of both of said pistons.

2. In an electric circuit interrupter comprising a pair of relativelymovable contacts, a first fluid motor including a cylinder and pistonfor producing relative movement of said contact-s, an auxiliary fluidmotor including a piston arranged initially to apply a mechanical forceto said first the movement of said contacts for quickly separating them,a fluid motor including a piston acting in a direction to continue theseparation of said contacts, means for introducing fluid under pressureto said piston only after said accelerating means has initiated themovement of said contacts, and fluid means to oppose said contactmovement durin the initial portion and final portion but not during anintermediate portion of the circuit interrupting operation.

5. In an electric circuit interrupter comprising a pair of relativelymovable contacts, a fluid operated motor including a cylinder and pistonfor producing relative movement of said contacts, an auxiliary meansarranged initially to apply a mechanical force to said contacts to causerelative separation thereof, means for rendering said auxiliary meansineffective after a predetermined movement thereof, means responsive toa predetermined movement of said auxiliary means for causing fluid underpressure to be introduced into said fluid operated motor after apredetermined movement of said contacts, and fluid operated means foropposing movement of said contacts during all but an intermediateportion of the opening operation of said circuit breaker.

6. In an electric circuit interrupter comprising a, pair of relativelymovable contacts, a first fluid operated motor including a cylinder andpiston for producing relative movement of said contacts, an auxiliaryfluid motor including a piston arranged initially to apply a mechanicalforce to said contacts to cause relative separation thereof, means forintroducing fluid under pressure to said auxiliary fluid motor withreference to said above mentioned fluid motors to cause movement of bothof said pistons and relative separation 01" said contacts, means forarresting said piston of said auxiliary fluid motor after apredetermined movement thereof, means responsive to movement of saidpiston of said auxiliary fluid motor for causing fluid under pressure tobe introduced into said first fluid operated motor after a predeterminedmovement of said contacts, and fluid operated means for opposingmovement of said pistons during all but an intermediate portion of theopening operation of said circuit breaker,

7. In an electric circuit interrupter comprising a pair of relativelymovable contacts, operating means for said contacts comprising anaccelerating means acting through a limited part of the movement of saidcontacts for quickly separating them, a fluid motor including a pistonacting in a direction to continue the separation of said contacts, meansfor introducing fluid under pressure to said piston only after saidaccelerating means has initiated the relative separation of saidcontacts, means for producing a blast of fluid adjacent said relativelymovable contacts upon separation thereof to extinguish the are drawnbetween said contacts, said blast of fluid tending to aid the separationof said contacts with one of said contacts efiectively acting as apiston, and means for compensating for the eflect of said blast of fluidon said one contact effectively acting as a piston only while said onecontact is effectively acting as a piston.

8. In an electric circuit interrupter comprising a pair of relativelymovable contacts, operating means for said contacts comprising anaccelerating means acting through a limited part of the movement of saidcontacts for quickly separating them, a fluid motor including a pistonacting in a direction to continue the separation of said contacts, meansfor introducing fluid under pressure to said piston only after saidaccelerating means has initiated the relative separation of saidcontacts, means for producing a blast of fluid adjacent said relativelymovable contacts upon separation thereof to extinguish the are drawnbetween said contacts, said blast of fluid tending to aid the separationof said contacts with one of said contacts effectively acting as apiston, means for compensating for the efiect of said blast of fluid onsaid one contact effectively acting as a piston, and means for renderingsaid compensating means ineffective upon cessation of said blast offluid.

JULIUS W. TIMMERMAN, JR.

BEFERENCES CITED The following references are of record in the flle ofthis patent:

UNITED STATES PATENTS Number Name Date 1,756,307 Rowntree Apr. 29, 19302,055,815 Dewey Sept, 29, 1936 2,148,616 Gruber Feb. 28, 1939 2,360,687Johnson Oct. 17, 1944 2,363,283 Baker et al. Nov. 21, 1944

